1. Field of Invention
This invention relates generally to a water distribution system, and in particular to a water distribution system having a dual use water treatment unit.
2. Background of the Invention
Water treatment units (WTUs) for the purification of potable water on aircraft or other vehicles have been known for years. For example, International Water-Guard Industries Inc. provides different models of flight-certified water treatment units for aircraft applications.
Certain known WTUs employ ultraviolet (UV) lamps that inactivate micro-organisms including pathogens by irradiation with UV light in the germicidal wavelength range. This process is customarily referred to as UV disinfection. The WTUs sometimes are also supplied with either sediment or activated carbon filters for the removal of fine particulate matter or dissolved chlorine or organic matter to improve the taste of the water.
In known aircraft water treatment systems, WTUs are generally installed in one of two locations on an aircraft. They may be installed at the exit of a potable water storage tank so that all the water delivered from the tank to aircraft points of use is disinfected, whether the water is delivered under pressure to points of use on demand or water is circulating continuously. Alternatively, WTUs may be installed at selected points of use on the aircraft, such as galleys where food and beverages are prepared or for VIP showers.
Aircraft manufacturers or aircraft completion centers have enquired about treating water as it is being uploaded onto the aircraft on the ground. Proposed solutions have included integrating additional WTUs into the aircraft potable water fill system. These proposals are not optimal due to the additional cost of WTUs that would be used during the fill operation, and the weight and complexity of the WTUs should they be installed on the aircraft. Another drawback is that past proposals for WTUs to be used for fill operations are installed further from the point of water use and thus are generally regarded as providing less protection to human health since there is more opportunity for contamination downstream of the treatment units.